I won't assume, so I went with the measurements given. And there's a thing called mathematics. One can compute a triangles legs with 2 lengths given and also knowing the degrees that are given and known. The top tubes of either bike is within .003 of each other, while the seat tube is 56 cm for both. I don't need to really do the calculation to know the down tube and unknown for the EAI has gotta be about the same length & dimension to comprise the main triangles of both bikes. Then again the steering tube is 136 for the Surly and the the BK is 167 mm, that 21 mm being longer and the down tube could be a tad shorter too. But the seat tube angle is identical for both bikes and the standover height being less than 1/8" difference tells me the bikes are essentially the same knowing the other dimensions are as nearly identical as well. Both bikes have level top tubes also, so it's not as though one has a sloping top tube. Guess we were fortunate in that aspect of both frames ? The rear triangle and even the fork has to have enough dimensions & rake to accomodate front & rear 700c wheels radius. Eyeballing the clearances for both tires are essentially the same.